The present invention relates to surface coverings including floor coverings. The present invention more particularly relates to surface coverings, such as floor coverings having an interlocking design to connect individual pieces of floor plank or tile together. The present invention further relates to methods of making the surface covering.
Some of the current surface coverings, such as vinyl floor coverings, are typically laid down by placing an adhesive underneath the floor covering or on the sub-floor or on the underlayment in order to secure the floor covering. In resilient floor coverings, a large piece of resilient floor covering is typically cut in order to fit the dimensions of the room. The resilient floor coverings can often be 12-foot wide and can be any length, such as 12 feet, 20 feet, or longer. With this type of surface covering, it is necessary to adhere the resilient surface covering, such as vinyl sheet flooring, to the sub-floor, underlayment or floor surface in order to keep the surface covering in place and also to achieve a surface covering that is level and does not curl. The installation process of using full-spread adhesive is very time consuming, costly, messy as well as cumbersome. For instance, an installer in general has to do the floor preparation first to remove all oil, dirt, grease, wax, sealers, paint, adhesives or any other substances that would hinder installation. In addition, the subfloor must be level without major pot holes or cracks; the conditions of the subfloor such as moisture content, structure soundness, etc., also have to be taken care of before the adhesive is applied. On the adhesive part, the selection of the right type of adhesive based on the type of subfloor is critical. The proper tools such as trowel type and its size are important for achieving the best economics and performance. After the adhesive is applied, it requires a proper opening time for the adhesive to develop its tackiness before the floor is put down. Any residuals of adhesive oozing up to the surface of the flooring need to be removed quickly before they set and adhere to the flooring surface. Furthermore, the adhesive cost can be quite expensive. The best advantage of the floating floor installation is that products can be directly installed on the existing floor materials without major prep work or removing the existing floor. This is a tremendous benefit for any subfloor for instance, having asbestos content, where any disruption of the subfloor structure can be extremely hazardous to the installer's health.
With all the reasons mentioned above, it should not be a surprise that the design of floating floors has recently become almost necessary as a surface covering. For instance, laminate flooring is used, wherein the laminate flooring typically is a rigid floor plank that can be joined together using a mechanical locking system, wherein one side of the floor plank has a tongue profile and the adjacent floor plank has a groove profile which permits the joining of the two through a mechanical locking system. While this mechanical laminate flooring system has gained great popularity in the United States, there are several problems with this type of flooring. First, the flooring can be extremely heavy since the core of the floor plank is typically made out of a wood-based material, such as a lignocellulosic-resin composite material, such as high density fiber board or particle board. Further, this fiber or particle board is typically not water resistant and also can be insufficiently resistant to even humidity changes. Thus, the laminate flooring can be limited where it is used since if the wood-based core became moist and swelled, this would damage the flooring and the laminate joined floor planks would actually separate.
While some attempts have been made to provide flooring surfaces made out of vinyl that simulate floor planks, these designs have not addressed all of the problems associated with previous flooring products, such as the location of adhesives, failure to use mechanical locking systems, design features that permit easy joining of flooring planks together, and the like. There has been some attempt to use PVC-type floor panels with a lockable tongue and groove connection as, for instance, described generally in U.S. Patent Application Publication No. 2008/0138560 and U.S. Pat. No. 4,426,820. In the floor panel set forth in U.S. Patent Application Publication No. 2008/0138560, only general designs are shown in the figures, and there is no clear teaching on precise tongue and groove profiles with regard to parameters, such as height, width, angles, and the like regarding the tongue profile and groove profile. However, the illustrated figures of tongue and groove locking designs set forth in the indicated publication are either based on cantilever hook or arrowhead designs. The designs of the indicated publication are believed to have disadvantages in installation or joint strength. In the indicated publication, FIG. 2a shows a tongue interlockable with a sloped land at the end of the bottom side of a groove, wherein the tongue can be provided with sufficient thickness to achieve a good joint strength, but it is believed that the locking design can require significant effort to force the opening of a relatively narrow mouth of a groove for the hook part of the tongue to go in. This process may require using a tapping block or other devices with a hammer, which adds complexity for the installer and also increases the risk of damaging the product. On the contrary, if the tongue is thin to permit flexing for ease of connection, this can result in weak joint strength. In the indicated publication, FIGS. 2b, 2c and 2d show no sloped, inclined land in the groove to restrict the tongue from sliding apart from the groove after engagement which can result in a very weak joint strength. The typical joint strength of this type of design is less than 5 pounds of force per linear inch (pli). FIG. 2e of the indicated publication is expected to have even more problems for similar reasons.
With respect to U.S. Pat. No. 4,426,820, the '820 patent exemplifies a plastic tongue and groove profile for flooring. The plastic flooring of the '820 patent is made from hard plastic and is not flexible. The flooring of the '820 patent has tongue and groove characteristics similar to many current commercial laminate flooring made from rigid, high-density fiberboard or medium-density fiberboard. In the designs of the '820 patent, many sharp edges in the tongue and groove profiles are used, and this can generate problems with fit during installation. Additionally, the overall strength of the tongue and groove profiles, when joined together (joint strength), will be lessened by high stress concentrations associated with the sharp edges. In addition, the groove lip top surface plan of the designs in the '820 patent are horizontal, which can make insertion of the tongue into the groove difficult, which can be an especially important problem when inserting short ends of a panel in the short ends of an already engaged adjoining panel. Also, the tongue and groove profiles of the '820 patent have a tongue tip cross-sectional area, which is relatively small and can be one-third the area of certain embodiments of the present invention. This is further explained in the details of the present invention. Also, the groove deck cross-sectional area in the groove profile of the '820 patent is disproportionate compared to the tongue tip cross-sectional area, which engages this groove deck area. This can be especially important when dealing with thinner product applications, such as residential luxury vinyl tiles, wherein the tongue tip will not provide enough integrity to facilitate installation if the groove deck cross-sectional area is disproportionate to the tongue tip cross-sectional area. As shown in the present invention, a balanced or proportionate tongue tip cross-sectional area to groove deck cross-sectional area will permit overloading of groove voids during insertion, and the tongue and groove will flex to accommodate one another and produce a firm product fit. This firm fit assures stability through the duration of the installation and for the life of the installed product. A disproportionate groove deck area at the tongue tip area will not permit overloading of the void. In addition, in various profiles of the present invention, the tongue profile and/or groove profile can have slants in various edges as opposed to straight horizontal edges, which permits easier insertion of the tongue into the groove and also permits alternative ways to install the product (meaning, that the groove can be inserted into the tongue, angle insertion of one profile into another is possible, as well as lateral (no angle) insertion). Thus, with the present invention, significant improvements over the various tongue and groove profiles of the '820 patent are achieved, as well as permitting a tongue and groove design that will provide sufficient joint strength and operability in a luxury vinyl tile-type product, as well as other resilient floor products.
Furthermore, as described in the present application, not just any tongue design or groove design can be used with vinyl-type flooring to achieve acceptable connecting properties, such as pull strength or joint strength. The inventors of the present application have discovered that particular tongue and groove profiles are necessary in order to achieve acceptable pull strengths and other suitable properties which will work with respect to resilient-type flooring, such as vinyl flooring, such as LVT flooring. The problems encountered and the solutions achieved by the present invention simply were not described, predicted, or appreciated previously. The present invention overcomes these problems and provides a surface covering product that is easy to install, requires no adhesive on the bottom surface of the surface covering or sub-floor, is water resistant, achieves acceptable pull strengths or joint strengths, and/or other connecting properties, and permits a floating floor that is relatively lightweight compared to laminate flooring and provides a walking surface that is more realistic to solid wood flooring, even from the standpoint of acoustic sounds.